The present invention relates to systems and methods for recovering and separating lube oils, and in a further embodiment relates to methods and apparatus for separating heavy dewaxed lube oils, especially bright stock into light and heavy products.
Manufacturing methods for separating heavy lube base oil products, including bright stock, into salable, higher value, higher quality light and heavy products are known. The use of direct fired heat to heat the material to the necessary temperatures to be treated and separated has the possibility of hot spots in the heater tubes which risks undesirable product degradation. The use of steam to strip the oil requires an additional drying treatment to insure the final product remains as dry as the feed stream, an unattractive process complication. The use of steam ejectors as motive energy for producing the vacuum will require additional waste treatment, which is preferably avoided. The use of flash separation requires operation at vacuums below those felt to be within prediction method ranges. Modification of upstream processing facilities to produce light and heavy bright stock products is possible. However, this will usually require additional tankage, more severe processing conditions, and higher capital and operating costs.
It is desirable for a process to be provided which separates heavy dewaxed lube oil without these process complications, but without any decrease in product quality.
Accordingly, it is an object of the present invention to provide a process and system for separating heavy dewaxed lube oil which can use equipment familiar to the refining industry.
It is additionally an object of the present invention to provide a process and system for separation of heavy dewaxed lube oil, including bright stock, which avoids product degradation.
It is further an object of the invention to provide a process for separating heavy dewaxed lube oil which does not require additional drying treatments.
Another object of the invention is to provide a process and system for heavy dewaxed lube oil separation which does not require additional waste treatment, and which operates in a parameter range where prediction methods and modeling may be used.
In carrying out these and other objects of the invention, there is provided, in one form, a process for separating heavy dewaxed lube oils, including heating a heavy dewaxed lube oil stream; injecting the heated heavy dewaxed lube oil stream into a vacuum stripper; injecting a gas stripping medium at the bottom of the stripper; removing a light lube oil fraction from an upper portion of the stripper; and removing a heavy lube oil fraction from the bottom of the stripper.